Prosthetic cardiac valve

ABSTRACT

A prosthetic atrio-ventricular or pulmonary valve for permanent cardiac implantation comprising a tubular valve body formed with two or more angularly spaced outwardly projecting sinus like bulges in its wall, and not appreciably extending axially in either direction beyond the bulges so that the external shape of the valve body is pseudo barrel shaped. The valve body contains a number of thin flexible impermeable cusps one registering with the internal hollow provided by each bulge. Each cusp is sealed to the valve body along its upstream and axially extending edges but has a free downstream edge which terminates in the axial direction short of the downstream edge of the corresponding hollow and which has a length such that when the valve is open the cusps can surround a substantially cylindrical passageway through the valve but when the valve is closed the free downstream edges of the cusps can meet and seal against those of the adjacent cusps along radial planes. The arrangement is such that the downstream edge of the hollows provided by the bulges intercepts part of the flow through the valve so that vortices are set up in the hollows tending to close the cusps.

United States Patent [1 1 Bellhouse et a].

[451 July 10, 1973 PROSTHETIC CARDIAC VALVE [76] Inventors: Brian John Bellhouse, The Ridings,

lslip; Francis Hewitt Bellhouse, 34 Hill Rise, Old Woodstock, both of England 22 Filed: June 10, 1971 211 App]. No.: 151,741

[52] US. Cl 3/1, 3/DIG. 3, 137/5251 [51] Int. Cl A611 1/22, F161: 15/14 [58] Field of Search 3/1, DIG. 3;

[56] References Cited UNITED STATES PATENTS 1 3,579,642 5/1971 Heffernan et al 3/1 3,130,418 4/1964 Head et a1. 3/1

FOREIGN PATENTS OR APPLICATIONS 1,932,817 1/1970 Germany 3/DIG. 3

Primary Examiner-Richard A. Gaudet Assistant Examiner-Ronald L. Frinks Attorney-Holcombe, Wetherill & Brisebois [5 7] ABSTRACT A prosthetic attic-ventricular or pulmonary valve for permanent cardiac implantation comprising a tubular valve body formed with two or more angularly spaced outwardly projecting sinus like bulges in its wall, and not appreciably extending axially in either direction beyond the bulges so that the external shape of the valve body is pseudo barrel shaped. The valve body contains a number of thin flexible impermeable cusps one registering with the internal hollow provided by each bulge. Each cusp is sealed to the valve body along its upstream and axially extending edges but has a free downstream edge which terminates in the axial direction short of the downstream edge of the corresponding hollow and which has a length such that when the valve is open the cusps can surround a substantially cylindrical passageway through the valve but when the valve is closed the free downstream edges of the cusps can meet and seal against those of the adjacent cusps along radial planes. The arrangement is such that the downstream edge of the hollows provided by the bulges intercepts part of the flow through the valve so that vortices are set up in the hollows tending to close the cusps.

10 Claims, 6 Drawing Figures PATENTED JUL 10 8975 SHEET 2 0F 2 PROSTHETIC CARDIAC VALVE The natural atrio-ventricular valves in the human heart, that is the mitral valve in the left ventricle and the tricuspid valve in the right ventricle act as nonreturn valves which control the blood flow from the atrium into the ventricle through an orifice in their dividing membrane, during the heart cycle. The natural valve comprises flexible cusps, two in the case of the mitral valve and three in the case of the tricuspid valve, which are attached to the periphery of the orifice and extend into the ventricle. Upon ventricular filling, blood is drawn from the atrium into the ventricle and the cusps of the valve move apart to open the valve and to allow the blood flow to take place. Upon ventricular contraction the cusps move together and close the valve.

Difficulties have previously existed in providing prosthetic atrio-ventricular valves particularly because the prosthetic valve must be implanted in the orifice in the thin wall dividing the atrium and ventricle rather than in a duct as in the case of a prosthetic aortic valve. Accordingly a part of the prosthetic valve must project into at least one of the atrium or ventricle and this disturbs'the natural blood flow and promotes thrombosis.

Our research indicates that the atrio-ventricular valves have similar characteristics to the aortic and pulmonary valves in that when the valves are open the cusps provide a substantially cylindrical passageway for the blood so that it flows with a laminar flow, the cusps being urged to their closed position by a ring vortex established within the ventricle and behind the cusps by the blood flow, together with a pressure difference tending to close the valve due to flow deceleration in the latter part of ventricular filling. The vortex persists when the blood flow decelerates so that the cusps approach their closed position before there is any appreciable backflow. The difference is that in the case of the aortic valve the vortices are set up in the sinuses in the wall of the aortic root. This is described more fully in U.S. Pat. No. 3,608,097 and US. patent application Ser. No. 151,740. in the case of the atrio-ventricular valve the vortices formed behind the cusps in the ventricle appear to be produced by the flow of blood through the valve impinging on the far wall of the ventricle and being forced to flow back along the side walls of the ventricle.

The similar characteristics of the atrio-ventricular and aortic valves, for example in promoting laminar flow when open and in having cusps which are urged to a closed position by vortices produced by the flowing blood, has suggested to us that a prosthetic atrioventricular valve could be built on the model of the aortic valve, provided that the difficulties resulting from having to implant the valve in the orifice can be overcome.

in accordance with the present invention a prosthetic valve for permanent cardiac implantation comprises a tubular valve body formed with two or more angularly spaced outwardly projecting sinus like bulges in its wall, and not appreciably extending axially in either direction beyond the bulges so that the external shape of the valve body is pseudo barrel shaped, and the valve body containing anumber of thin flexible impermeable cusps one registering with the internal hollow provided by each bulge, each cusp being sealed to the valve body I along its upstream and axially extending edges but having a free downstream edge which terminates inthe axial direction short of the downstream edge of the corresponding hollow and which has a length such that when the valve is open the cusps can surround a substantially cylindrical passageway through the valve but when the valve is closed the free downstream edges of the cusps can meet and seal against those of the adjacent cusps along radial planes and the arrangement being such that the downstream edges of the hollows provided by the bulges intercept part of the flow through the valve so that vortices are set up in the hollows tending to close the cusps.

A valve of this construction should operate satisfac torily since it takes account of and uses the hydrodynamic properties of blood as indicated by our research. We also believe that this construction avoids the previous problems of prosthetic atrio-ventricular valves by virtue of the external pseudo barrel shape of the valve body. By pseudo barrel shape is meant substantially barrel shaped but not exactly of circular section owing to the presence of the angularly spaced bulges.

The valve body will be sewn into the orifice in the ,atrio-ventricular membrane wall by means of a suture ring which may be attached at any appropriate axial position along the outside of the valve body. The actual position of the sewing ring will depend upon whether the surgeon wishes the valve to be implanted so that it projects more into the atrium or more into the ventricle or equally into both. This could depend for example on unusual enlargement of one or other of the atrium and ventricle. However the valve body is implanted, it will present a substantially convex projection on both sides of the atrio-ventricular membrane wall and we believe that this shape will be continually swept on the one side by the atrial swirl and on the other side by the ventricular vortex so that there will be no tendency for excessive clot-formation around the implanted valve.

We also believe that the valve in accordance with the invention is useful as a whole root replacement for the pulmonary valve. In this application the valve body will be provided with a sewing ring at each end.

The valve body should be shape sustaining and provide a secure mounting for the cusps without being so hard that it irritates the adjacent parts of the heart as they move naturally. We therefore make the valve body from a woven or knitted textile fabric, preferably a fine uncut terylene velour which may be reinforced with a silicone rubber. The tubular body may be made up with two layers of the velour bonded together with the silicone rubber. This produces a resilient body which has a certain ability to move with the heart but has no rigid skeleton. The uncut velour, of which the suture ring may also be made, has the advantage of providing a surface into which natural tissue will grow and readily knit.

At present we make the cusps from a woven or knitted terylene fabric coated with silicone rubber.

Although two, four, five or even more cusps are possible, we believe that three cusps and, correspondingly, three bulges, are preferred on the model of the aortic valve. However since the atrio-ventricular valve is asymmetrically situated in the ventricle, the blood flow leaving the valve will be asymmetrical and accordingly it may be necessary for the size of the bulges and cusps to be asymmetric in the prosthetic valve. For example it may be necessary to provide a larger bulge and cusp on the side of the valve which will be adjacent to the larger vortex side of the ventricle.

One example of a prosthetic mitral valve constructed in accordance with the present invention, and its use, are illustrated in theaccompanying drawings, in which:

FIG. 1 is a downstream end elevation of the valve with parts broken away in section and showing the valve closed;

FIG. 2 is a section taken on the line IIII in FIG. 1;

FIG. 3 is an elevation similar to FIG. 1 but showing the valve open;

FIG. 4 is a section taken on the line IVIV in FIG.

FIG. 5 is a diagrammatic view showing the prosthetic valve implanted in the heart; and,

FIG. 6 is a broken perspective view of the valve.

The valve comprises a tubular body formed by three arcuate portions 6, 7 and 8. Each arcuate portion is a laminate incorporating inner and outer layers 9 and 10 of terylene velour bonded together by an intervening layer 11 of silicone rubber. The three arcuate portions are stitched together along their abutting generally axially extending edges. The tubular body thus formed is flexible and produces an oblate barrel shaped body with three sinus like bulges or lobes providing three equiangularly spaced internal hollows 12.

Three cusps 13, made of ten denier warp knitted terylene fabric coated with silicone rubber, are mounted within the tubular body, one cooperating with each sinus hollow 12. Each cusp is slightly trapezoidal in shape, the two inclined edges 14 of each cusp being stitched and bonded between the adjacent edges of the corresponding adjacent arcuate portions 6, 7 and 8 and .the shorter edge of each cusp being stitched and bonded to the edge, which is lowermost in FIG. 2, of the corresponding arcuate portion. The free edge 15 of each cusp is slightly greater than 11/3 of the diameter of the circle which just touches the inner surface of the tubular body, that is at the points where the arcuate portions meet one another.

The sinus like hollows 12 project axially a little beyond the edges 15 of the cusps so that when blood flows through the valve the cusps will open to form an unobstructed cylindrical passage 22 for laminar flow, as shown in FIGS. 3 and 4. In an analogous manner to that occurring naturally in the aortic .valve, the arcuate portions 6, 7 and 8 intercept part of the flow through the valve causing ring vortices to be set up in the sinus like hollows 12 tending to urge the cusps radially inwards. As soon as the flow decelerates therefore the cusps move inwardly until their edges 15 abut one another along equiangularly spaced radial planes of contact 16 thus closing the valve and preventing back flow.

As shown in FIG. 5, the prosthetic mitral valve 17 will be secured in the mitral opening 18 between the atrium and the left ventricle 19. The aortic root is shown at 20. The valve is located by means of a suture ring 21 which is also shown in the other Figures of the drawings, and which consists of a strip of terylene velour which is sewn into a tube and the tube then sewn to the outside of the tubular body of the valve. When the valve is implanted the ring is sewn to the edge of the mitral opening. We find that the velour is extremely acceptable to the natural tissue which readily grows into and knits with the velour.

The axial position at which the suture ring 21 is sewn to the valve body depends upon the extent to which the pseudo barrel shaped valve body is required by the surgeon to project into the left ventricle or intothe atrium.

For the avoidance of doubtit should be pointed out that in FIG. 5 the implanted prosthetic mitral valve 17 controls the flow downwards from the atrium into the left ventricle 19 and accordingly is shown in FIG. 5 the opposite way up to that in which it is shown in FIGS. 2, 4 and 6. In other words the upstream end of the valve as shown in FIGS. 2, 4 and 6 is lowermost.

An analogous construction and implantation may be used for a prosthetic tricuspid valve.

We claim:

1. A prosthetic valve for permanent implantation in a cardiac orifice, said valve comprising a tubular valve body formed with at least two angularly spaced outwardly projecting sinus-like bulges in its wall defining internal hollows extending nearly the full length of the body, whereby the external shape of said valve body is convex in axial section, a peripheral suture ring secured to the outside of and extending around said convex body and a number of thin flexible impermeable cusps within said body, one registering with the internal hollow provided by each bulge, each cusp being sealed to said valve body along upstream and axially extending edges but having a free downstream edge which terminates in the axial direction short of said downstream edge of the corresponding hollow and which has a length such that when said valve is open said cusps can surround a substantially cylindrical passageway through said valve and the downstream edge of said hollows intercepts part of the flow through the valve so that vortices are set up in said hollows tending to close the cusps, but when said valve is closed said free downstream edges of said cusps can meet and seal against those of the adjacent cusps along radial surfaces.

2. A valve according to claim 1, wherein there are three substantially equiangularly spaced bulges.

3. A valve according to claim 1, wherein said valve body is made from a textile fabric.

4. A valve according to claim 3, wherein said textile fabric is a fine uncut terylene velour.

5. A valve according to claim 3, wherein said valve body is formed as a laminate from at least two layers of fabric from which said suture ring is made is a fine lene fabric is a ten denier warp knitted fabric.

* t i t Patent No. 3 37 0 Dated July 10 973 Inventor(s) BRIAN JOHN BELLHOUSE and FRANCIS HEWITT BELLHOUSE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected' as shown below:

[73] Assignee: National Research Development Corporation,

London, England Signed and sealed this 27th day of November 1973.

(SEAL) Attest:

EDWARD M.FLETCHER ,JR. Attesting Officer RENE 1). TEGTMEYER I Acting Commissioner of Patents FORM Po-1o5o (10-69) USCOMM-DC 60376-P69 F u.s. GOVERNMENT PRINTING OVFFIICE: l9" 0-366-334. 

1. A prosthetic valve for permanent implantation in a cardiac orifice, said valve comprising a tubular valve body formed with at least two angularly spaced outwardly projecting sinus-like bulges in its wall defining internal hollows extending nearly the full length of the body, whereby the external shape of said valve body is convex in axial section, a peripheral suture ring secured to the outside of and extending around said convex body and a number of thin flexible impermeable cusps within said body, one registering with the internal hollow provided by each bulge, each cusp being sealed to said valve body along upstream and axially extending edges but having a free downstream edge which terminates in the axial direction short of said downstream edge of the corresponding hollow and which has a length such that when said valve is open said cusps can surround a substantially cylindrical passageway through said valve and the downstream edge of said hollows intercepts part of the flow through the valve so that vortices are set up in said hollows tending to close the cusps, but when said valve is closed said free downstream edges of said cusps can meet and seal against those of the adjacent cusps along radial surfaces.
 2. A valve according to claim 1, wherein there are three substantially equiangularly spaced bulges.
 3. A valve according to claim 1, wherein said valve body is made from a textile fabric.
 4. A valve according to claim 3, wherein said textile fabric is a fine uncut terylene velour.
 5. A valve according to claim 3, wherein said valve body is formed as a laminate from at least two layers of said textile fabric with a layer of silicone rubber sandwiched therebetween.
 6. A valve according to claim 1, wherein said tubular body is made from a number of arcuate portions each shaped to provide one of said bulges.
 7. A valve according to claim 1, wherein said suture ring is made of a textile fabric.
 8. A valve according to claim 7, wherein said textile fabric from which said suture ring is made is a fine uncut terylene velour.
 9. A valve according to claim 1, wherein each cusp is made from a fine terylene fabric coated with silicone rubber.
 10. A valve according to claim 9, wherein said terylene fabric is a ten denier warp knitted fabric. 